"I am in charge of the bachelorette party [and the bridal] shower," Marquardt told Usmagazine.com at the opening of Jane's House in Hollywood Friday.
Wilkinson, who is marrying Philadelphia Eagles' Hank Baskett on June 27 at the mansion, is filming all the wedding festivities for her new E! reality show, Kendra.
"They have asked me to collaborate with them," Marquardt tells Us. "They are looking into a couple different venues right now. They have to pick the venue because of filming and permits and all that kind of stuff. The film crew wants to come with me to scout a few different locations this week."
Why the responsibility? Marquardt, 35, is going to be a bridesmaid in the wedding -- along with former roommate Holly Madison.
"There are other girls, too," Marquardt says, adding that she took Wilkinson wedding dress shopping but still needs to do some fittings for her own dress. "Some playmates and her best friend from San Diego. I think there are five of us all together. It is not too big of a wedding."
Marquardt, who has been out of the country filming her Travel Channel show for seven months, wishes she could have done more.
"[One day,] I helped her plan it out and told her to remember to do this, think about this, think about that," she tells Us. "I helped her figure out where it is going to be and how it is going to work out."
At the upcoming lavendar-colored nuptials, Wilkinson will be walked down the aisle by her brother, and ex-boyfriend Hugh Hefner will be in the audience, Marquardt tells Us.
Speaking of weddings, will Marquardt -- who is dating director Nick Carpenter, 29 -- be planning one of her own anytime soon?